Search for: hydroxyapatite
0.007 seconds
Total 107 records

    Rapid synthesis of hydroxyapatite nanopowders by a microwave-assisted combustion method

    , Article Journal of Ceramic Processing Research ; Volume 13, Issue 3 , Jan , 2012 , Pages 221-225 ; 12299162 (ISSN) Bovand, N ; Rasouli, S ; Mohammadi, M. R ; Bovand, D ; Sharif University of Technology
    Nano bioactive hydroxyapatite (Ca 10(PO 4) 6(OH) 2, HAp) ceramic powders have been synthesized by a microwave-assisted combustion method. The powders were synthesized using calcium nitrate tetrahydrate (as the source of calcium) and sodium phosphate dibasic anhydrous (as the source of phosphate ions). Glycine, citric acid and urea were used as fuesl. The influence of the fuel type on the structure and morphology of the samples was studied. Results by X-ray diffraction and Fourier-transform infrared spectroscopy showed the formation of hydroxyapatite as a major phase for all the samples. Using the Scherrer formula, the average crystallite size was found to be in the range of 10 to 28 nm.... 

    The wet precipitation process of hydroxyapatite

    , Article Materials Letters ; Volume 57, Issue 24-25 , 2003 , Pages 4064-4069 ; 0167577X (ISSN) Saeri, M. R ; Afshar, A ; Ghorbani, M ; Ehsani, N ; Sorrell, C. C ; Sharif University of Technology
    Stoichiometric hydroxyapatite (HA) powder was synthesized by wet method using orthophosphoric acid and calcium hydroxide, as raw materials. In this regard, the time-depending changes of the precipitated particles and effects of heating on them were investigated. The as-precipitated and heated powder samples were examined using field emission electron microscopy (FESEM), XRD and Raman spectroscopy methods. The results revealed that the morphology and size of the precipitated particles change in each stage of the process. After drying, these nanoparticles tend to form small agglomerates. © 2003 Elsevier Science B.V. All rights reserved  

    Some important factors in the wet precipitation process of hydroxyapatite

    , Article Materials and Design ; Volume 24, Issue 3 , 2003 , Pages 197-202 ; 02641275 (ISSN) Afshar, A ; Ghorbani, M ; Ehsani, N ; Saeri, M. R ; Sorrell, C. C ; Sharif University of Technology
    Elsevier Ltd  2003
    The precipitation process considered here, involved the addition of orthophosphoric acid solution to a calcium hydroxide solution. Several parameters such as the effects of atmosphere controlling, pH, adding extra acid solution, the amount of stirring speed, and post-chemical treatment were studied. In order to study the thermal stability of synthesised powders, they were sintered for 2 h at 1200 °C and the as-precipitated and sintered powder samples were examined using SEM, XRD, FTIR and ICP methods. The results clearly revealed that the final precipitated powder is hydroxyapatite (HA) with good purity, stoichiometry and successful thermal stability. SEM high magnification micrographs... 

    Fabrication mechanism of nanostructured HA/TNTs biomedical coatings: an improvement in nanomechanical and in vitro biological responses

    , Article Journal of Materials Science: Materials in Medicine ; Volume 27, Issue 10 , 2016 ; 09574530 (ISSN) Ahmadi, S ; Riahi, Z ; Eslami, A ; Sadrnezhaad, S. K ; Sharif University of Technology
    Springer New York LLC  2016
    In this paper, a mechanism for fabrication of nanostructured hydroxyapatite coating on TiO2 nanotubes is presented. Also, the physical, biological, and nanomechanical properties of the anodized Ti6Al4V alloy consisting TiO2 nanotubes, electrodeposited hydroxyapatite, and the hydroxyapatite/TiO2 nanotubes double layer coating on Ti6Al4V alloy implants are compared. Mean cell viability of the samples being 84.63 % for uncoated plate, 91.53 % for electrodeposited hydroxyapatite, and 94.98 % for hydroxyapatite/TiO2 nanotubes coated sample were in the acceptable range. Merely anodized prototype had the highest biocompatibility of 110 % with respect to the control sample. Bonding strength of... 

    Grit blasting of Ti-6Al-4V alloy: Optimization and its effect on adhesion strength of plasma-sprayed hydroxyapatite coatings

    , Article Journal of Materials Processing Technology ; Volume 194, Issue 1-3 , 2007 , Pages 15-23 ; 09240136 (ISSN) Mohammadi, Z ; Ziaei Moayyed, A. A ; Mesgar, A. S. M ; Sharif University of Technology
    Elsevier BV  2007
    The effect of grit blasting parameters on the surface roughness of Ti-6Al-4V alloy as the substrate for plasma-sprayed hydroxyapatite (HA) coatings was examined using the factorial and Taguchi designs of experiments. In this study, two grit materials (Al2O3 and SiO2) each at two sizes, and two types of blasting systems (pressure and suction) were used. An equivalent surface roughness of 3.51 μm was obtained in three optimum conditions. The results of the Taguchi designed experiments were analyzed using signal to noise ratio. The tensile bonding strength of HA coatings deposited on the roughened substrates at the three different optimum conditions was measured by the standard adhesion test... 

    Synthesis of Composite Coating with HA Nanoparticles on Ti by AC Plasma Electrolyte Oxidation

    , M.Sc. Thesis Sharif University of Technology Soleymani Naeini, Masih (Author) ; Ghorbani, Mohammad (Supervisor)
    In this project, a ceramic biocompatible coating was applied on Titanium which is included Hydroxyapatite by AC Plasma Electrolyte Oxidation method. First, coating was performed in 5 different solutions and various duration in 500mA/Cm2 as a current density. Then, by microscopic and macroscopic images and size of porosity and also thickness of coat, 3 solutions were chosen for adding nanoparticles: Solution 1 which includes NaH2PO4 and Ca(CH3COO)2 , Solution 3 which includes Ca(CH3COO)2 and Na-Beta G and Solution 4 which includes Ca(H2PO4)2, HMP, NA2(EDTA) and Ca(CH3COO)2 . Also the time 10 minutes was chose as a appropriate time. The average of the porosities size in solution 1 was about... 

    Effect of Mullite Content on HAp-Mullite Composite for Hard Tissue Application

    , M.Sc. Thesis Sharif University of Technology Rahmani, Marzieh (Author) ; Faghihi Sani, Mohammad Ali (Supervisor) ; Solati Hashjin, Mehran (Supervisor)
    In this study effect of various mullite contents, as reinforcement phase, on phase combination, fracture surface and mechanical propertiese of hydroxyapatite- mullite composite has been investigated.
    The used hydroxyapatite powder was synthesized through acid- base route and further calcination. XRD results demonstrated partially decomposition of HA in to β- TCP and CaO during the calcination. SEM image of the prepared HA powder showed that they were spherical and agglomarated.
    The mixed HA with various amounts of the ball- milled mullite (10- 40 wt%)were pressed and sintered at 1350°C for 2h. Dominant phase in all composite samplese after sintering was Ca9Al(PO4)7.

    Synthesis of Hydroxyapatite Nanoparticles through Sol-Gel Method and Fabrication of Chitosan/Hydroxyapatite Scaffold for Bone Replacement Tissue

    , M.Sc. Thesis Sharif University of Technology Behboodi, Panteha (Author) ; Nemati, Ali (Supervisor) ; Faghihi Sani, Mohammad Ali (Co-Supervisor)
    Hydroxyapatite is the most substantial inorganic component of bone tissue which displays great biocompability and bioactivity. Nevertheless, its mechanical properties is not appropriate for a bone substitiues. Therefore, it is used to improve the mechanical properties of polymer matrix composite scaffolds. In the present work chitosan as a polymeric matrix was employed to fabricate hydroxyapatite- chitosan biocomposite scaffolds. Sol-Gel method was employed to synthesize hydroxyapatite nano particles. Porous scaffolds were fabricated via freeze-drying by introducing two different cross linkers, Glutaraldehyde and Sodium Tripolyphosphate. Mechanical (compressive strength), biocampability and... 

    Chitosan/Gelatin/Mg Substituted Hydroxyapatite Nano Composite Scaffold for Bone Tissue Engineering

    , M.Sc. Thesis Sharif University of Technology Azamian, Fariba (Author) ; Mohammadi, Mohammad Reza (Supervisor) ; Fathi, Mohammad Hossein (Co-Advisor)
    The present study is work on fabrication and characterization of a chitosan/ gelatin/ Mg substituted hydroxyapatite nano composite scaffold for bone tissue engineering. At the first step pure and Mg-substituted hydroxyapatite (HA) (Ca10-xMgx(PO4) 6OH2) nano-hexagonal rods with 14–45 nmdiameter.for this, calcium nitrate, magnesium phosphate hydrate and potassium dihydrogenphosphate were used as precursors for Ca, Mg, and P, respectively. Calculated amounts of magnesium ions (Mg+2) especially from 0 to 8% (molar ratio) were incorporated as substituted into the calcium sol solution. Deionized water was used as a diluting media for HA sol preparation and ammonia was used to adjust the pH= 9.... 

    Preparation and Characterization of Hydroxyapatite Nanostructures Using Natural Resources for Bone Scaffold Applications

    , M.Sc. Thesis Sharif University of Technology Gheysari, Hengameh (Author) ; Simchi, Abdolreza (Supervisor) ; Askari, Masoud (Supervisor)
    This investigation presents synthesis and characterization of pure and monophasic hydroxyapatite (Ca10(PO4)6(OH)2; HA) Nanostructures prepared by coral and oyster shell powders heated at 800 oC for 8 h as precursor via precipitation method. The morphology of HA nanostructures was controlled in the presence of various surfactants such as SDS, CTAB and PVP. The HA Nanorods synthesized by SDS were applied to fabricate bone scaffolds. Particle sizes of the HA Nanoparticles were about 20-30 nm. Pours three-dimensional HA/Ge/CMC scaffolds cross-linked by citric and oxalic acids were synthesized. In order to increase the pore size of the scaffolds, NaCl with medium (180-250 µm) and large (420-500... 

    Preparation of Hydroxyapatite-Graphene Nano Composite Coating on Ti-6Al-4V Alloy Using Plasma Electrolyte Oxidation

    , M.Sc. Thesis Sharif University of Technology Mohammadipour, Erfan (Author) ; Ghorbani, Mohammad (Supervisor)
    Hydroxyapatite-Graphene Nanocomposite coatings were formed on Ti-6Al-4V alloy by Plasma electrolytic oxidation. PEO electrolyte contains calcium acetate and calcium glycerophosphate. The effect of adding graphene to PEO electrolyte on the corrosion, mechanical, and biocompatibility properties of the coating investigated. Before adding graphene to the electrolyte, working parameters such as voltage, current density, process time were optimized using scanning electron microscopy (SEM), potentiodynamic polarization test, and thickness measurement. Examination of the coating morphology showed that due to thermal stresses, surface cracks formed at Voltages above 350 V. The results of the... 

    Highly efficient hydroxyapatite/TiO2 composites covered by silver halides as E. coli disinfectant under visible light and dark media

    , Article Photochemical and Photobiological Sciences ; Volume 12, Issue 10 , October , 2013 , Pages 1787-1794 Azimzadehirani, M ; Elahifard, M ; Haghighi, S ; Gholami, M. R. (Mohammad Reza) ; Sharif University of Technology
    TiO2-based photocatalysts are seen as the most common agents for the photodegradation of bacteria. In this study, AgCl/TiO2, hydroxyapatite(Hp)/AgCl/TiO2, AgI/TiO2, and Hp/AgI/TiO2 were prepared by the deposition-precipitation method on P25 TiO2 nanoparticles and were characterized by XRD, SEM, FT-IR, EDX and BET methods. The prepared composites showed high efficiency for the inactivation of Escherichia coli (E. coli) bacteria under visible light and in dark media with different catalyst amounts of 12 and 24 mg, respectively. In less than 30 min, AgI/TiO2, prepared by the combination of cationic surfactant and PVPI2, disinfected 1 × 10(7) colony-forming units of E. coli completely. However,... 

    Crystallisation kinetics of hydroxyapatite thin films prepared by sol-gel process

    , Article Advances in Applied Ceramics ; Volume 109, Issue 6 , Jul , 2010 , Pages 313-317 ; 17436753 (ISSN) Najafi, H ; Nemati, A ; Sadeghian, Z ; Sharif University of Technology
    In this study, the crystallisation of nano hydroxyapatite (HA) films on stainless steel 316L was studied. The film was prepared by sol-gel technique. The process was started with preparation of an HA sol. After aging of the sol at room temperature, a stainless steel 316L substrate was dip coated and then was heat treated from 350 to 450°C at different periods of time in air. The crystallisation behaviour and the transformation-temperature-time diagram of HA films were achieved and analysed using the avrami equation. The results showed that the crystallisation of HA began at 250°C and was increased up to 450°C. The obtained HA film showed a nanostructure character with a suitable crystalinity... 

    Electrophoretic deposition of porous hydroxyapatite coatings using polytetrafluoroethylene particles as templates

    , Article Materials Science and Engineering C ; Volume 27, Issue 5-8 SPEC. ISS , 2007 , Pages 1482-1486 ; 09284931 (ISSN) Yousefpour, M ; Afshar, A ; Chen, J ; Zhang, X ; Sharif University of Technology
    The formation of macroporous bioactive hydroxyapatite(HA) coatings using polytetrafluoroethylene(PTFE) particles were studied. The porous HA coatings were prepared onto a pure titanium substrate by electrophoretic deposition(EPD) at 120 V for 1.5 min using ethanol suspensions mixture of HA (500 nm in size) and PTFE (1-3 μm in size) particles. Subsequently, the composite coatings obtained by EPD were heated at 900 °C for 60 min to disintegrate the organic PTFE particles and sinter the inorganic HA particles. The calcinations of the PTFE led to the formation of porosity in the HA coating. These results demonstrate a new method for creating porous HA coatings on titanium. © 2006 Elsevier B.V.... 

    , M.Sc. Thesis Sharif University of Technology (Author) ; Ghorbani, Mohammad (Supervisor)
    In the preceding years, hydroxyapatite (HA)-based coatings and scaffolds have been known as the best biomaterials for dental and orthopedics applications. Biocompatible and bioactive hydroxyapatite-based Coatings on metallic implants is one of the best methods for reaching both suitable mechanical properties and appropriate bioactivity, leading to better osseointegration and osteoblast proliferation. The ultimate goal of this project is characterization as well as mechanical and electrochemical behavior investigation of Hydroxyapatite- Chitosan nanocomposite coating by electrophoretic deposition (EPD) method on Plasma Electrolyte Oxidation (PEO) treated titanium substrates and Magnesium (Mg)... 

    Development of electrophoretically deposited hydroxyapatite coatings on anodized nanotubular TiO2 structures: Corrosion and sintering temperature

    , Article Applied Surface Science ; Vol. 301 , May , 2014 , pp. 250-257 ; ISSN: 01694332 Goudarzi, M ; Batmanghelich, F ; Afshar, A ; Dolati, A ; Mortazavi, G ; Sharif University of Technology
    Hydroxyapatite (HA) coatings in and onto anodized TiO2 nanotube arrays were presented and prepared by electrophoretic deposition technique (EPD). Coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). EPD proved to be an innovative and versatile technique to coat HA on and into nanotubular structures of TiO2 with enhanced adhesion between nanotubes and HA particles provided by mechanical interlocking. After EPD of HA on TiO2 layer, samples were sintered at 400 °C, 600 °C and 800 °C for 2 h in an Ar atmosphere. Effect of EPD processing parameters on thickness of the deposits and rate of deposition was elucidated for HA coatings on the nanotubular TiO2... 

    In vitro characterization of carbon-nanotube-reinforced hydroxyapatite composite coating on 316L stainless steel

    , Article Journal of Ceramic Science and Technology ; Volume 4, Issue 3 , August , 2013 , Pages 163-168 ; 21909385 (ISSN) Mohamadi, S. P ; Nemati, A ; Sadeghian, Z ; Sharif University of Technology
    This investigation focused on a comparison between hydroxyapatite (HA) and carbon-nanotube-reinforced hydroxyapatite composite (CNTs/HA) coatings. The HA and CNTs/HA composite (with 5wt% CNTs) coatings were prepared with the sol-gel method on 316L stainless steel. Phase evaluation by means of XRD and Raman spectroscopy was performed on the HA and CNTs/HA composite coatings. The coatings were immersed in simulated body fluid (SBF) in order to evaluate the biological properties of the coatings. During the first week of immersion, the increase in the amount of Ca2+ precipitation in the SBF when CNTs/HA was used was lower than for the HA coatings. This behavior can be related to the difference... 

    Surface modification for titanium implants by hydroxyapatite nanocomposite

    , Article Caspian Journal of Internal Medicine ; Volume 3, Issue 3 , 2012 , Pages 460-465 ; 20086164 (ISSN) Family, R ; Solati Hashjin, M ; Nik, S. N ; Nemati, A ; Sharif University of Technology
    Background: Titanium (Ti) implants are commonly coated with hydroxyapatite (HA). However, HA has some disadvantages such as brittleness, low tensile strength and fracture toughness. It is desirable to combine the excellent mechanical properties of ZrO 2 and the chemical inertness of Al 2O 3 with respect to the purpose of this project which was coating Ti implants with HA-ZrO 2-Al 2O 3 to modify the surface of these implants by adding ZrO 2 and Al 2O 3 to HA. The purpose of this study was to evaluate the efficacy of hydroxyapatite coating nonocomposite. Methods: From September 2009 to January2011, functionally graded HA-Al 2O 3-ZrO 2 and HA coatings were applied on Ti samples. HA-Al 2O 3-ZrO... 

    Rapid growth of hydroxyapatite nanoparticles using ultrasonic irradiation

    , Article Ultrasonics Sonochemistry ; Volume 17, Issue 5 , Jun , 2010 , Pages 853-856 ; 13504177 (ISSN) Rouhani, P ; Taghavinia, N ; Rouhani, S ; Sharif University of Technology
    A rapid, environmental friendly and low-cost method to prepare hydroxyapatite nanoparticles is proposed. In this method, hydroxyapatite is produced in a sonicated pseudo-body solution. The sonication time was found effective in the formation of the crystalline phase of nanoparticles. In our experimental condition, 15 min sonication resulted in the most pure hydroxyapatite phase. Also it was shown that growth temperature is a crucial factor and hydroxyapatite crystallizes only at 37 °C. The particles formed by sonication were generally smaller and more spherical than those obtained without sonication. Sonication increased the hydroxyapatite crystal growth rate up to 5.5 times compared to... 

    Loading drug on nanostructured Ti6Al4V-HA for implant applications

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 31, Issue 8 , 2018 , Pages 1159-1165 ; 1728144X (ISSN) Abbaspour, S ; Sadrnezhaad, S. K ; Sharif University of Technology
    Materials and Energy Research Center  2018
    Arrayed Ti6Al4V nanotubes (TNT) coated with hydroxyapatite (HA) were synthesized via electrochemical anodization method. Paracetamol was loaded onto TNT-HA electrode. Effects of anodization, nanotube formation and hydroxyapatite deposition on sorption and release of the drug were investigated. Saturation time of paracetamol on the anodized samples was 30% shorter than the hydroxyapatite-coated samples. Release behavior of the loaded drug was studied by (a) plunging the probe into phosphate buffered saline (PBS), (b) sampling the drug-loaded PBS at different times and (c) analyzing the solution via ultraviolet-visible (UV-vis) spectroscopy. Results showed that HA electrodes hold higher...